The newly-released document was filed in May 2011 and is highly detailed. If a product comes to market it could challenge Google's Project Glass.

Google is planning to deliver its augmented reality glasses to developers early next year and then follow with a release to consumers in 2014. Smaller firms — such as Vuzix, TTP and Explore Engage — are also working on rival systems.

Although some have questioned how many people would want to wear such devices, a recent report by Juniper Research indicated that the market for smart glasses and other next-generation wearable tech could be worth $1.5bn by 2014 and would multiply over following years.